1. Field of the Invention
This invention relates to check valve inserts for use with conventional plumbing "T" type couplings to make ball-type check valves which are particularly adapted for use in manholes that drain into storm sewers or ditches.
2. Description of the Prior Art
A common check valve design utilizes a "T" shaped casing having a vertically oriented inlet port through which fluid may pass vertically to exit via a laterally extending outlet port. Such designs commonly employ a valve seat in the inlet port and a ball closure member or "check ball" which is moveable in a substantially vertical direction. To prevent loss of the check ball through the outlet port, some devices provide enlarged cavities between the inlet and outlet ports to permit the use of a check ball having a diameter greater than that of the outlet port. However, casings for such devices generally need to be custom manufactured which renders fabrication relatively complicated and expensive.
U.S. Pat. No. 3,648,729 issued Mar. 14, 1972 to John W. Balkany shows a valve insert assembly for converting an ordinary pipeline "T" coupling into a ball type check valve which thus obviates the need for fabrication of a special casing. The Balkany insert includes a spring which surrounds the check ball to constrain it to movement in a substantially vertical direction.
Another method for preventing loss of the check ball through the outlet port is shown in U.S. Pat. No. 2,278,715 issued Apr. 7, 1942 to Ludwig T. Stoyke et al, which discloses use of an apertured guide sleeve to surround the check ball and constrain it to movement in a substantially vertical direction.
The spring (in the Balkany device) and the sleeve (in the Stoyke device) serves to guide the check ball to and from the valve seat.
Although either of the Balkany or Stoyke devices may be used in conventional pipeline "T" couplings, they are susceptible to accumulation around the valve seat area of solid material which may be present in the fluid passing through the valve. Such accumulations may eventually result in fluid leakage past the check ball when the ball is in the "closed" or seated position. Furthermore, the Stoyke device is said to operate most satisfactorily when the clearance between the check ball and the guide sleeve is less than a specific amount. At some point, a minimum clearance between the check ball and the guide sleeve will be reached below which accumulations of solid material may inhibit free movement of the check ball within the guide sleeve eventually resulting in leakage past the check ball. Both the Balkany and Stoyke devices must be disassembled to provide access to the valve seat area for removal of accumulated deposits therefrom. This problem is exacerbated where the device is to be installed, for example to control drainage from a manhole into a sewer or ditch, because relatively substantial amounts of solid foreign matter may enter the valve assembly.
It is an object of the present invention to provide a check valve insert for use with a conventional pipeline "T" coupling which enables easy access for cleaning to remove accumulated deposits of solid material without necessitating disassembly or removal of the insert from the "T" coupling. A related object is to provide a check valve insert which is constructed to inhibit accumulation of particulate foreign matter which may interfere with free movement of the check ball or prevent adequate sealing engagement of the check ball with the valve seat.